This invention relates to an anti-vibration bush adapted to be used for industrial machines, automobiles and so forth to absorb vibrations.
An anti-vibration bush used for industrial machines, automobiles and so forth is disposed between a vibration generating member and a vibration receiving member. The anti-vibration bush has an outer casing, a shaft, and rubber therebetween. The rubber restricts relative translation and relative rotation between the outer casing and the shaft to absorb vibrations.
In addition, an improved anti-vibration bush is known and used, and has the following features: the interior of the rubber is divided into a plurality of small liquid chambers; these liquid chambers are sealingly filled with water or the like; and these liquid chambers are in communication with each other through orifices so that vibrations are absorbed by the resistance against flow of the water or the like passing through the orifices when vibrations are generated (See Japanese Patent Unexamined Publication No. 203242/1983).
However, such a conventional anti-vibration bush has a problem in that, although vibrations of an expected frequency can be absorbed, vibrations of different frequencies cannot sufficiently be absorbed because of the constant dimensions of the orifice. To solve this problem, some anti-vibration bushes have restricted paths which can be opened and closed. Such an anti-vibration bush, however, cannot absorb vibrations over a wide range of frequencies.